Scrub washing method

ABSTRACT

A scrub washing apparatus comprises a spin chuck for holding a substrate to be processed substantially horizontally, a nozzle for supplying a washing liquid to the substrate mounted on the spin chuck, an arm vertically and horizontally movably supported, an output shaft provided at the arm, a sponge brush connected directly or indirectly to the output shaft, for scrubbing the substrate on the spin chuck in contact therewith, a press mechanism moving the sponge brush downward together with the output shaft, for pressing the sponge brush against the substrate on the spin chuck, and a rotation drive mechanism provided above the press mechanism at a position where the rotation drive mechanism is capable of being engaged with the output shaft, for directly rotating the sponge brush by engaging with the output shaft.

This is a division of U.S. patent application Ser. No. 09/281,531 filedMar. 30, 1999, now U.S. Pat. No. 6,292,972.

BACKGROUND OF THE INVENTION

The present invention relates to a scrub washing apparatus and scrubwashing method for washing a substrate such as a semiconductor wafer andan LCD glass substrate.

In manufacturing steps of semiconductor devises, a single-processingsubstrate washing system is used for removing contaminants, such asparticles, organic compounds, and metal ions, attached to a surface of asemiconductor wafer. The single-processing substrate washing system hasa scrub washing apparatus for scrubbing away attached materials(contaminants) from the surface of the wafer by brining a brush or asponge (hereinafter referred to as “scrub member”) into contact with thewafer in rotation.

The scrub washing apparatus has a swingable horizontal arm, a verticaloutput shaft arranged at a tip portion of the horizontal arm, a scrubmember directly or indirectly supported by the vertical output shaft, arotation drive means for driving the rotation of the scrub membertogether with the vertical output shaft, and a press means for pressingthe scrub member downward together with the vertical output shaft. Acontact pressure of the scrub member to the substrate (hereinafterreferred to as “scrub contact pressure”) corresponds to a total force ofa press force given to the scrub member by the press means and a weightof the scrub member itself. The surface of the substrate is desirablywashed by properly controlling conditions including the scrub contactpressure, a rotation speed of the scrub member, a moving speed of thescrub member, and a rotation speed of the substrate, in accordance withthe surface state of the substrate.

Such a scrub apparatus is disclosed in Japanese Patent Application KOKAIpublication Nos. 8-141518, 8-141519. In these conventional apparatuses,an expandable bellows mechanism and an air cylinder mechanism areemployed as the press means. For example, in the bellows mechanismdescribed in Japanese Patent Application KOKAI 8-141518, the press forceis applied to the vertical output shaft by expanding and contracting ofthe bellows fitted at an upper end of the vertical output shaft. In theair cylinder mechanism, the press force is applied from the cylinder tothe vertical output shaft by protruding or retracting a piston rodattached to an upper end of the vertical output shaft. However, in theconventional apparatuses, if a rub resistance between the verticaloutput shaft and a bearing is changed, the press force may not bedesirably transmitted to the scrub member. Since a belt mechanism isused as a rotation drive mean in the conventional apparatus, therotation force may not be desirably transmitted to the scrub memberbecause the tension of the belt varies. Furthermore, a driving forcetransmission mechanism of the conventional apparatus is complicated instructure since numerous mechanical elements such as a belt, a pulley, abellows, an air cylinder, and a bearing, are assembled, resulting ingeneration of particles in a non-negligible amount. The generatedparticles are attached to the substrate, degrading the cleanliness ofthe substrate surface.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a scrub washingapparatus and method capable of transmitting a desired press force and arotation driving force to a scrub member without fail and generating fewamount of particles.

According to the present invention, there is provided a scrub washingapparatus comprising:

a mounting table for holding a substrate to be processed substantiallyhorizontally;

a washing liquid supply mechanism for supplying a washing liquid to thesubstrate mounted on the mounting table;

an arm vertically and horizontally movably supported;

an output shaft provided at the arm;

a scrub member connected directly or indirectly to the output shaft, forscrubbing the substrate on the mounting table in contact therewith;

a press mechanism moving the scrub member together with the outputshaft, for pressing the scrub member against the substrate on themounting table; and

a rotation drive me chanism provided above the press mechanism at aposition where the rotation drive mechanism is capable of being engagedwith a the output shaft, for directly rotating the scrub member byengaging with the output shaft.

In this case, the o utpu t shaft has an upper portion extending upwardfrom the press mechanism, a driven engage member attached to the upperportion, and a lower portion extending downward from the press mechanismand connected to the scrub member; and

the rotation drive mechanism has a rotation drive shaft extendingdownward and a drive engage member attached to a lower end of therotation drive shaft.

The apparatus further comprises a liftable moving mechanism for movingthe output shaft up and down to the press mechanism. The liftable movingmechanism moves up the output shaft to engage the driven engage memberwith the drive engage member, thereby transmitting the rotation driveforce from the rotation driving mechanism to the output shaft.

The drive engage member preferably has

a first connection board connected to the rotation drive shaft;

a horizontal support shaft attached to the first connection board; and

a pair of rollers supported by the horizontal support shaft.

The driven engage member preferably has

a second connection board connected to the output shaft;

a plurality of vertical projections respectively standing at corners ofthe second connection board; and

depressed portions formed between two adjacent projections.

The output shaft is moved up by the liftable moving mechanism to engagethe depressed portions with the pair of rollers, thereby transmittingrotation driving force from the rotation drive mechanism to the outputshaft.

The driven engage member has a plurality of projections extending indirection of the rotation drive shaft. Depressed portions are formedbetween two adjacent projections. The drive engage member is engagedwith the depressed portions.

According to the present invention, there is provided a scrub washingmethod of scrubbing a substrate with a scrub member while a washingliquid is supplied to the substrate by transmitting a press force and arotation driving force to the scrub member by means of an output shaftand a rotation drive shaft, which comprises the steps of:

(a) setting a scrub contact pressure when the substrate is scrubbed withthe scrub member, the output shaft being engaged with the rotation driveshaft and arranged on an extension line of the rotation drive shaft;

(b) mounting the substrate on a mounting table;

(c) moving the scrub member above the substrate mounted on the mountingtable;

(d) moving down the scrub member together with the output shaft;

(e) transmitting a rotation drive force to the output shaft from therotation drive shaft to rotate the scrub member; and

(f) adjusting the pressing force of the scrub member to the substrate atthe scrub contact pressure set at the step (a).

In the conventional apparatus, since the rotation drive shaft is locatedat a distance from the output shaft, a rotation driving force istransmitted to the output shaft from the rotation drive shaft by way ofa belt and a pulley. Since the rotation driving force is transmittedindirectly, the output shaft is likely to be affected by variousexternal disturbances (change in tension of a belt), with the resultthat up-and-down movement and rotation movement of the output shaftbecome unstable.

In contrast, in the apparatus of the present invention, since therotation drive shaft is located immediately above the output shaft, therotation driving force is transmitted directly from the rotation driveshaft to the output shaft. Since the rotation driving force is directlytransmitted as described, the output shaft is not affected by theexternal disturbances, with the result that the up-and-down movement andthe rotation movement of the output shaft become stable.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a schematic perspective view of a substrate washing system,shown partly cutaway;

FIG. 2 is a schematical plan view of the scrub washing apparatus;

FIG. 3 is a longitudinal sectional view of the scrub washing apparatus;

FIG. 4 is an inner perspective view of a driving section of the scrubwashing apparatus;

FIG. 5 is an inner perspective view of a support arm and a scrub member;

FIG. 6 is a perspective view showing that the drive engage section isengaged with the driven engage section according to the firstembodiment;

FIG. 7 is an exploded perspective view showing a drive engage section inengagement of a driven engage section according to a second embodiment;

FIG. 8 is a perspective sectional view showing the state where a driveengage member is engaged with a driven engage member.

FIG. 9 is a cross sectional view showing an inner structure of an aircylinder accompanying a block diagram of the peripheral elements; and

FIG. 10 is a block diagram showing a circuit of the air cylinderequipped with an electrical air supply regulator.

DETAILED DESCRIPTION OF THE INVENTION

Now, various preferred embodiments of the present invention will beexplained with reference to the accompanying drawings.

As shown in FIG. 1, a substrate washing system 1 has a loader/unloadersection 2, a process section 5, and transport arm mechanisms 3, 4. Theloader/unloader section 2 has a mounting table 2 a extending in anX-axis direction. In front of the mounting table 2 a, a cassettetransporting passage (not shown) is provided. A cassette C istransported by a transport robot (not shown) along the cassettetransporting passage and mounted on the mounting table 2 a. For example,four cassettes C are mounted on the mounting table 2 a. Each cassette Cstores 25 semiconductor wafers W which constitute one lot.

The sub transport arm mechanism 3 is arranged at a back surface side ofthe cassette mounting table 2 a. A wafer W is taken out of the cassetteC by the sub transport arm mechanism 3 and transferred to the maintransport arm mechanism 4 of the process section 5.

The process section 5 has the main transport arm mechanism 4 and twowashing units 7, 8, a dry unit 9, and a reverse unit 10. The maintransport arm mechanism 4 is movably arranged along a transport passage6 extending in the Y-axis direction. The washing units 7, 8 having asingle-processing scrub washing apparatus are arranged along one ofsides of the transport passage 6. The dry unit 9 and the reverse unit 10are arranged on the other side of the transport passage 6. The dry unit9 has a hot plate for heating the wafer W to dry. The reverse unit 10has a mechanism for turning over the wafer W so as to change an uppersurface to a lower surface of the wafer W. At the back surface side ofthe process section 5, a washing liquid supply apparatus (not shown) anda waste water collect apparatus (not shown) are arranged.

Each of the transport arm mechanisms 3, 4 has an arm portion, an X-axisdrive mechanism (not shown), a Z-axis drive mechanism (not shown), aθ-rotation mechanism (not shown), and an arm back-and-forth drivingmechanism (not shown). The arm portion is moved by the Z-axis drivemechanism (not shown) in the Z-axis direction, rotated around the Z-axisby the θ-rotation mechanism, and moved back and forth by the armback-and-forth moving mechanism. The X-axis drive mechanism, Z-axisdrive mechanism, θ-rotation mechanism, arm back-and-forth movingmechanism is controlled by a controller 73 shown in FIG. 5 on the basisof initially input data.

Now, referring to FIGS. 2-5, the first process unit 7 will be explained.As shown in FIGS. 2 and 3, the process unit 7 is surrounded by a case 20and having a loading/unloading port 7 a in the front surface side of thecase 20. The wafer W is loaded into and unloaded from the process unit 7through the loading/unloading port 7 a by the main transport armmechanism 4. A spin chuck 22 is provided at near a center of the case20. The spin chuck 22 has a mounting table 22 a, a plurality ofmechanical chucks (not shown) for holding the wafer W, and a motor 21for rotating the mounting table 22 a. The motor 21 is controlled by thecontroller 73. Incidentally, a vacuum adsorption mechanism may be usedin place of the mechanical chuck serving as the holding means for thewafer W.

A cup 23 is provided so as to surround the wafer W on the spin chuck 22.The cup 23 is used for receiving liquid scattered from the wafer W. Adrain 23 a is formed at the bottom of the cup 23. The waste water isdischarged from the cup 23 through the drain 23 a.

A scrub washing mechanism 25 and a washing liquid supply mechanism 87are arranged respectively at both sides of the cup 23. The scrub washingmechanism 25 has a scrub portion 24 having a sponge (scrub member) 85.The scrub portion 24 is provided at one end of the arm member 26. Thearm member 26 is supported substantially horizontally by a support rod39 covered with a cover 40 shown in FIG. 4.

As shown in FIG. 2, the washing liquid supply mechanism 87 is located soas to face the scrub washing mechanism with the spin shuck 22 interposedthere-between. A nozzle 87 a is attached to an arm tip portion of thewashing liquid supply mechanism 87. Pure water is supplied to the nozzle87 a from a liquid supply unit 88 (shown in FIG. 5). Note that an armswinging angle θ2 of the washing liquid supply mechanism is equal to aswinging angle θ1 of the arm member 26 of the scrub washing mechanism25.

As shown in FIGS. 2 and 3, a sensor 74 is provided at a home position inwhich the scrub portion 24 is stand-by when it is not used. The sensor74 measures a scrub contact pressure of the scrub portion 24. The sensor74 is formed of, for example, load cells which detect distortion byweight loading, in terms of a change in electrical resistance value. Thesensor 74 is brought into contact with the scrub portion 24 when thescrub portion is not in use, thereby determining the contact pressure.Data of the electric signal is obtained when the scrub contact pressureis equal to a desired pressure value on the basis of the determinationresults, and then stored in the control section 73. The “desiredpressure value” corresponds to the scrub contact pressure previouslyobtained by a trial washing test in which a dummy wafer DW isscrub-washed by the scrub portion 24 used in practice.

When the wafer is washed in practice, the controller 73 outputs thedesired pressure data from the memory and sends it to an electrical airsupply regulator 72 (shown in FIGS. 5 and 9) to control a supplypressure of air to be supplied to the air cylinder 50. In this way, thescrub contact pressure of the scrub portion 24 to the wafer W, can beproperly controlled. In this case, it is desirable that the height of ameasurement surface 74 a of the sensor 74 be equal to the height of theupper surface of the wafer W held by the spin chuck 22, as shown in FIG.3.

As shown in FIG. 4, a bracket 31 is fixed at a lower surface of the basetable 30 of the case 20. To the bracket 31, a cylinder 32 is attached. Arod 33 of the cylinder 32 supports a support board 36 on the uppersurface of which a motor 34 and a bearing 35 are arranged. The rotationdriving force of the motor 34 is transmitted to the bearing 35 through abelt 37.

An upper portion of the shaft 38 of the bearing 35 loosely threadsthrough the base table 30 and connected to a lower end portion of thesupport rod 39. An upper portion of the support rod 39 is fixed to aproximal end portion of the arm member 26. The shaft 38 and support rod39 are covered with slide covers 40 and 41. The lower cover 41 isconnected to the base table 30. The upper cover 40 is attached to thearm member 26. The upper cover 40 is larger in diameter than the lowercover 41. When the rod 33 is retracted into the cylinder 32, the uppercover 40 slidably moves to the lower cover 41, with the result that thesupport rod 39 moves up the scrub portion 24 together with the armmember 26.

As shown in FIGS. 4 and 5, the arm member 26 is constituted of a frame26 a and a cover 26 b and thus the inner space thereof is hollow. Toeliminate the particles generated in the hollow arm member 26, the innerspace of the arm member 26 is locally evacuated through the exhaust tube82. Furthermore, to eliminate the particles generated outside the armmember 26, the outer space of the arm member 26 is locally evacuatedthrough an exhaust tube 81.

The support rod 39 mentioned above is connected to a lower surface of aproximal end side of the frame 26 a. A scrub wash assembly 25 isattached to a distal end side of the frame 26 a. An upper half portionof the scrub wash assembly 25 is covered with the cover 26 b and theframe 26 a and thus hidden within the arm member 26. On the other hand,a lower half of the scrub wash assembly 25 protrudes downwardly out ofthe arm member 26 through an opening 26 c. The scrub portion 24 isattached to the lower half portion of the scrub wash assembly 25.

An air cylinder 50 is attached to the frame 26 a. The air cylinder 50has a output shafts 53 protruding upward and downward as the outputshaft. An upper portion 53 a of the rod can be engaged with a rotationdrive shaft 56 of a motor 52 via engage members 60, 64. A lower portion53 b of the rod is connected to the scrub 24 via an opening 26 c, acoupling 54 and a holder 55.

The scrub portion 24 is held by the holder 55. The holder 55 isdetachably attached to the coupling 54. The coupling 54 is detachablyconnected to the lower portion 53 b of the rod. The scrub portion 24 ofthis embodiment, whose weight is 170-220 g, has a scrub member 85 madeof sponge. As the scrub member 85, various sponges different in hardness(soft sponge to hard sponge) may be used. A soft sponge may be combinedwith a hard sponge as the scrub member 85. Such a scrub member 85 iscapable of washing the surface of the wafer softly and uniformly withoutscratching a pattern formation surface or a pattern formation planningsurface of the wafer W. Note that the scrub member may be a hard brushsuch as a hard-bristle nylon brush and a soft brush such as asoft-bristle mohair brush in accordance with an object to be washed.

As shown in FIG. 5, a seal ring 80 is attached to the lower surface ofthe frame 26 a so as to surround the lower portion (output rod) 53 b ofthe rod. The seal ring 80 has a depressed portion 80 a. An upper portion53 a of the coupling 54 is inserted to the depressed portion 80 a toengage with each other, thereby forming a labyrinth seal. Note that anexhaust tube 81 communicating with an exhaust apparatus 69 is attachedto the seal ring 80. The opening of the exhaust tube 81 is formed at thedepressed portion 80 a so as to exhaust the particles generated by rubmovement between the cylinder 50 and the lower portion 53 b, through theexhaust tube 81. Since such a local evacuation is made, the particlesmay not fall on the wafer W during the scrub washing.

The process liquid supply tube 86 communicating with the process liquidsupply unit 88 passes through the hollow arm member 26 and opened nearthe scrub portion 24. The process liquid supply unit 88 houses a purewafer supply source and a flow rate control valve. A power supply switch(not shown) of the flow rate control valve is connected to thecontroller 73. When the controller 73 sends an instruction signal to theprocess liquid supply unit 88, pure water is sent from the unit 88 to asupply pipe 86 and output from an output port of the supply pipe 86toward the scrub member 24.

Now, referring to FIG. 6, we will explain a rotation drive forcetransmitting mechanism for transmitting a rotation drive force of themotor 52 to output shafts 53.

The air cylinder 50, which is provided in the arm member 26, has anoutput shaft 53. The output shaft 53 has an upper portion 53 a of therod protruding upward of the cylinder 50 and the lower portion of therod 53 b protruding downward of the cylinder 50. As shown in FIG. 6, thedriven engage member 64 is attached onto the upper portion 53 a by meansof a screw 65. The driven engage member 64 has a second rectangularboard 64 a and four vertical projections 64 b. The vertical projections64 b stand on corners of the second rectangular board 64 a,respectively. Depressed portions 64c are formed between two adjacentvertical projections 64 a. To describe more specifically, the depressedportions 64 c are formed between two pairs of vertical projections 64 bstanding side by side along a short side of the second rectangular board64 a.

On the other hand, as shown in FIG. 5, the stepping motor 52 is attachedto an upper surface of the bracket 51 fixed on the air cylinder 50. Morespecifically, the air cylinder 50 and the motor 52 are individuallyfixed to a common bracket 51 in such a way that the motor 52 is locatedimmediately above the air cylinder 50. The rotation drive shaft 56 ofthe motor 52 extends downward and arranged concentrically in line withthe output shaft 53. To the rotation drive shaft 56, a drive engagemember 60 is attached. The drive engage member 60 has a firstrectangular board 61 connected to a rotation drive shaft 56, ahorizontal support shaft 62 and a pair of rollers 63. Each of the roller63 is rotatably supported by a side surface of the first rectangularboard 61 with the aid of a horizontal support shaft 62. The pair ofrollers 63 are arranged so as to correspond to a pair of depressedportions 64 c, as shown in FIG. 6.

When the output shaft 53 is moved upward to lift up the driven engagemember 64, the depressed portion 64 c is guided a long the roller 63 tomove up the driven engage member. Thereupon, the rotation drive force ofthe motor 52 is transmitted directly to the output shaft 53 through theengage members 60, 64. At the same time, pressing force of the cylinder50 is directly transmitted to the output shaft 53.

As shown in FIG. 5, an exhaust tube 82 is attached to the bracket 51.The opening of the exhaust tube 82 is formed near the portion at whichthe drive engage member 60 is engaged with the driven engage member 64to exhaust the particles generated at the engage portion. Note that theexhaust tube 82 is merged with a lower exhaust tube 81 at a mergeportion 83 and communicates with a suction port of the vacuum exhaustapparatus 69. In this way, attachment of the particles to the wafer Wcan be efficiently prevented by the local evacuation.

Now, referring to FIGS. 7 and 8, another rotation driving forcetransmitting mechanism will be explained.

The rotation driving force transmitting mechanism according to anotherembodiment has a drive engage member 160 and a driven engage member 165.The drive engage member 160 has a cylindrical portion 161 having a hole161 a and three first projections 162 attached in the outer periphery ofthe cylindrical portion 161. To the hole 161 a of the cylindricalportion 161, a tip portion of the rotation drive shaft 56 is fitted intoand combined therewith. The drive engage member 160 is rotated by themotor 52.

On the other hand, the driven engage member 165 has a disk portion 163and three second projections 164 attached around an upper surface of thedisk portion 163. To the lower surface of the disk portion 163, anoutput shaft 53 a of the air cylinder 50 is connected. When the outputshaft 53 is allowed to protrude upward from the cylinder 50, each of thesecond projections 164 is fitted between the adjacent first projections162. Since the driven engage member 165 is engaged with the drive engagemember 160, the rotation driving force of the motor 52 is ready totransmit directly to the output shaft 53. Note that the engage members160, 165 are made of polyethylene terephthalate (PET) resin.

As shown in FIG. 9, an air supply chamber 50 a and exhaust-air supplychamber 50 b are formed inside the air cylinder 50. Two air supply pipes71, 77 are individually communicated with the air supply chamber 50 a. Aair supply pipe and an air exhaust pipe 78 are individually communicatedwith the exhaust-air supply chamber 50 b. The exhaust-air supply chamber50 b is located above the air supply chamber 50 a and both chambers arecommunicated with each other.

As shown in FIG. 10, the exhaust pipe 78 communicates with the exhaustair supply chamber 50 b. The air supply pipe 77 communicates with an airsupply apparatus 68, whereas the air supply pipe 71 communicates with anair supply apparatus 67 by way of the electrical air supply regulator72. The controller 73 is connected to the power supply 66 of theelectrical air supply regulator 72 to control the air supply to the airsupply chamber 50 a by the controller 73.

Note that the exhaust pipe 78 is an open passage for releasing an innerpressure of the cylinder 50 outside.

The air supply apparatuses 67, 68 are discretely provided in thisembodiment. However, air may be supplied from a common air supplyapparatus to each of the two air supply pipes 71, 77. Note that air isalways supplied to the air supply chamber 50 a and the exhaust airsupply chamber 50 b from the air supply pipe 77. In contrast, air issupplied from the air supply pipe 71 only when the scrub member 85presses to the wafer W.

The air supply pipe 77 is branched into two flow passages 77 a, 77 bwithin the air cylinder 50. An opening of the branched passage 77 a isformed within the exhaust-air supply chamber 50 b. An opening of thebranched passage 77 b is formed within the air supply chamber 50 a. Airbearings 75, 76 are formed in the passages 77 a, 77 b, respectively. Anair cushion is formed in a slit between the rod 53 and the bearings 75and 76 by supplying air. Since rub resistance between the rod 53 and thecylinder 50 is reduced by the bearings 75, 76, the scrub washingapparatus is excellent in abrasion resistance and produces few amount ofparticles. Note that the air bearings 75, 76 are made of porous ceramicin the form of a ring.

As shown in FIG. 9, a ring-form stopper 70 is attached to a piston rod53 serving as an output shaft inside the air cylinder 50. The stopper 70is provided in the air chamber 50 a of the air cylinder 50, therebypreventing the output shaft 53 from coming out of the cylinder 50. Notethat the stopper 70 may be formed within the exhaust air supply chamber50 b.

During the scrub washing process, the stopper 70 can be kept in contactwith neither upper sheet 50 c nor lower sheet 50 d within the air supplychamber 50 a as shown in FIG. 9. As described, it is possible to controlthe scrub contact pressure at 20 gf or less by applying thrust upwardlyto the output shaft 53. The scrub contact pressure can be changed to,for example, 10 gf, 20 gf, 30 gf, 40 gf, or 50 gf by controlling thepower supply source of the electrical air supply regulator 72 of thecontroller 73.

Now, we will explain the case where the wafer W is scrub-washed by usingthe scrub washing apparatus mentioned above.

First, a shutter is opened, and then, the wafer W is loaded into theunit 7 through the loading/unloading port 7 a and mounted on the spinchuck 22. The wafer W is held by the spin chuck 22 and rotated at apredetermined speed. Then, the arm member 26 is rotated and the scrubportion 24 is located above a rotation center of the wafer W. The outputshaft 53 is moved up to engage the driven engage member 64 (165) withthe drive engage member 60 (160). Subsequently, a rotation driving forceof the motor 52 is transmitted from the rotation drive shaft 56 to theoutput shaft 53 to rotate the scrub portion 24. Since the rotationdriving force is transmitted directly to the output shaft 53, it becomeseasy to control the rotation speed of the scrub portion 24.

While the scrub 24 is placed in a home position (stand-by position), thepressing force to be applied to the output shaft 53 is previously set ata value equal to the predetermined scrub pressure.

The arm member 26 is moved down by the cylinder 32 to bring the rotatingsponge 85 into contact with the upper surface of the wafer W. Note thatthe weight of the scrub portion 24 is set at, for example, 200 gf.Furthermore, the scrub contact pressure is adjusted at 20 gf or less bycontrolling air supply to the air supply chamber 50 a of the aircylinder. In this case, thrust of the output shaft 53 working upwardlyis controlled by air supply pressure, so that the scrub contact pressureof the scrub portion 24 can be smoothly controlled. The thrust of theoutput shaft 53 is not adversely affected while the thrust and rotationof the output shaft 53 are controlled, it becomes easy to control therotation of the scrub portion 24.

Furthermore, complicated transmission parts such as a belt or a pulleyare not required, so that rotation driving force of the motor 52 can betransmitted to the rod 53 by use of a simple mechanism. As a result, thestructure of the arm member 26 is simplified. In addition, no particlesare generated due to rubbing between the belt and the pulley, unlike theconventional case.

On the other hand, as shown in FIG. 9, since the movement of the rod 53is supported by the air bearings 75, 76 in the air cylinder 50, the rodis not rubbed with the bearing, unlike the conventional case.Furthermore, as shown in FIG. 5, when an exhaust apparatus 69 is driven,evacuation of air is initiated through the exhaust tubes 81, 82. Ifparticles are produced at the lower outer peripheral portion of the rod53, the drive engage member 60 and the driven engage member 65, they areexhausted by the exhaust tubes 81, 82. In this way, the particles can beprevented from being scattering beforehand.

If necessary, while pure wafer is output from a pure wafer supplypassage 86, the arm member 26 is rotationally moved at least from thecenter to the peripheral portion by operating the motor 34 to therebywash the surface of the wafer W uniformly. Thereafter, both the nozzle87 and the wafer W are moved upward. While pure water is supplied ontothe upper surface of the wafer W from the nozzle 87, the wafer surfaceis washed. After completion of the wash, attached solution is removedfrom the wafer W by rotating the spin chuck 22 at a high speed. In thisway, the surface of the wafer is dried. The wafer W is then unloadedfrom the unit 6.

According to the apparatus of the aforementioned embodiment, since therotation driving force is directly transmitted from the motor 52 to therod 53, the rod 53 is not affected by various external disturbances.Therefore, it becomes easy to control the pressing force and therotation of the scrub portion 24. As a result, a predetermined scrubcontact pressure can be stably obtained during the washing process,improving the reliability of the washing process.

Furthermore, since complicated parts such as a belt and a pulley are notrequired, the structure of the arm member 26 can be simplified and theproduction of particles within the arm member 26 can be prevented.Accordingly, it is possible to reduce the number of parts used in asurface processing apparatus 7 and mitigate load for assembly of theapparatus. Consequently, reduction in yield due to the particleattachment can be prevented.

In the foregoing, exemplary embodiments of the present invention will beexplained. However, the present invention is not limited to them and maybe modified in various ways. For example, the substrate is not limitedto a semiconductor wafer W as described in the embodiments. An LCDsubstrate, glass substrate, CD substrate, photomask, print substrate,ceramic substrate, and the like may be used.

According to the present invention, since the rotation driving force isdirectly transmitted to the output shaft, the output axis is notaffected by external disturbances (tension of the belt etc.). It followsthat the scrub contact pressure and rotation drive can be readilycontrolled. As a result, it is possible to obtain the scrub contactpressure stably during the processing and thus the reliability of theprocessing can be improved. Furthermore, since complicated transmittingparts such as a belt and a pulley, are not required, it is possible toconstruct the arm member simply and thus particles are prevented frombeing produced in the arm member. Therefore, it is possible to reducethat parts used in the processing apparatus and mitigate the loadrequired for assembly of the apparatus. As a result, it is possible toprevent a reduction in yield due to the particle attachment.

If the thrust of the output shaft working in a vertical direction iscontrolled by air supply pressure, the scrub contact pressure can besmoothly controlled. Furthermore, the up-and-down moving operation andthe rotational operation of the output shaft are supported by using airpressure, the bearing of the output shaft exhibits excellent rubresistance and abrasion resistance. Even if particles are produced, thescattering of particles can be prevented beforehand.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A scrub washing method of scrubbing a substratewith a scrub member while a washing liquid is supplied to the substrateby transmitting a pressing force and a rotation driving force to thescrub member by means of an output shaft and a rotation drive shaft, theoutput shaft being engaged with the rotation drive shaft and arranged onan extension line of the rotation drive shaft, and having a portion thatis located in an air cylinder, said portion being equipped with astopper, said washing method comprising the steps of: (a) measuring ascrub contact pressure applied to a sensor from the scrub member bybringing the scrub member into contact with the sensor at a homeposition, obtaining data of electrical signal when the scrub contactpressure becomes equal to a desired pressure on the basis of themeasuring results, and storing said data in a memory; (b) mounting thesubstrate on a mounting table; (c) moving the scrub member above thesubstrate mounted on the mounting table; (d) moving down the scrubmember together with the output shaft by supplying air around the outputshaft in the air cylinder; (e) transmitting a rotation drive force tothe output shaft from the rotation drive shaft to rotate the scrubmember; and (f) retrieving said data from the memory and adjusting thepressing force of the scrub member to the substrate such that the scrubmember applies the desired pressure to the substrate based on theretrieved data by supplying air towards the stopper in the air cylinderand applying thrust upwardly to the output shaft.
 2. The methodaccording to claim 1, wherein the steps (e) and (f) are initiated afterthe step (a).
 3. The method according to claim 1, wherein the step (f)is initiated before the step (b).
 4. The method according to claim 1,wherein, in the step (f), the pressing force of the scrub member iscontrolled by applying thrust upwardly to the output shaft.
 5. Themethod according to claim 1, wherein the substrate is rotated while thescrub member is in contact with the substrate.